Lec11 Neisseria and gram negatives Flashcards
What types of bacteria does spleen play essential defense role?
encapsulated organisms
How can polysacccharide vaccines be altered to create longer lasting immunity? Why?
- by conjugating them to proteins
- this helps because proteins are more immunogenic than protein
What are the visual differences between meningococcus and pneumococcus both of which can cause meningitis?
pneumococcus: gram pos, diplococci
meningococcus: gram neg, kidney bean shaped cocci
Who gets meningitis?
- peak incidence age 6 mo to 2 years
- conditions of overcrowding
- those with splenectomy
- those with late complement deficiencies
Where does neisseria meningitis colonize? how is it transmitted?
- colonized nasopharynx in healthy people
- causes life-threatening infection when reaches bloodstream or CNS
- transmitted by respiratory droplets
What are the virulence factors of N. meningitis?
- secretes IgA protease
- —- allows survival in respiratory tract
- pili
- —- mediate attchement to respiratory epithelium
- Opa and Opc proteins
- —- allow to be engulfed by respiratory cells
- capsule
- — antiphagocytic
- lipooligosaccharide
- — endotoxin that triggers sepsis
What is rash like in mengingococcemia?
- cap appear as petechiae, purpura, or hemorrhagic bullae
- always non-blanching
WHat happens when LPS endotoxin released?
- released when bacterial cell dies
- riggers fatal downstream events
How many serogroups in N mengingitidis? which are most important?
- 13 serogroups
- determined by polysaccharide capsule
- most important A, B, C, W-135
Which serogroups are in the polyvalent vaccine?
A, C, Y, W-135
Why are vaccines against group B mengingococcus complicated?
- B has a polysacchardie capsule similar in struct to human sialic acid
besides meningitis, what other infections is neisseria meningitidis associated with?
- meningococcemia
- respiratory tract infection
- pneumonia
- otitis media
- conjuncitivitis
- septic arthritis
- pericarditis
What is treatment for n. meningitidis?
- cephalosporins [ceftriaxone] most common
- pencillin [one of few gram neg that does not produce beta lactamase]
What is empiric treatment of bacterial meningitis [when no organism on gram stain]?
- ceftriaxone [against meningococcus, haemophilus, and pneumococcus]
- vancomycin [because of beta-lactam resistant pneumococcal strains]
- sometimes steroids [to minimize inflammatory response]
- sometimes ampicillin [against listeria]
What is shape of listeria monocytogenes?
- gram positive rod
- tumbling end of end motility
Who is most susceptible to listeria?
- infants and elderly [bimodal distribution]
- immunocompromised
- pregnant women
What drugs do and do not have activity against l. monocytogenes?
- cephalosporins do not have reliable activity
- ampicillin does have activity
When is mengitis chemoprophylaxis used?
- for close contacts of index case
- can prevent invasive disease if given within 14 days of exposure
How do you differentiate N. gonorrheoeae and N. meningitidis?
- N gonorrhoeae does not have true polysaccharide capsule
- N. gonorrhoeae only utilizes glucose
- N. meningitidis utilizes glucose or maltose
What are the virulence factors for N. gonorrhoeae?
- similar to N. meningitidis
- pili assist binding human mucosal surfaces
Which patients are most at risk for N. gonorrhoeae?
- 15-25 year old men and women highest rate
- high risk in patients with terminal complement deficiencies
What are symptoms of gonorrhea?
about 10% asymptomatic
- infection of genitals
- foul smelling purulent discharge
- inflammation, redness, dysuria
What are the diseases associated with N. gonorrhoeae?
- ophtalmia neonatorum: transmitted from mother to child in delivery
- pelvic inflammatory disease
- pharyngitis
- perihepatitis [fitz-hugh-curtis syndrome]
What are symptoms of pelvic inflmmatory disease?
- chronic infection causes damage to fallopian tubes, sterility, ectopic pregnancy
